Suspension Trailing Arm

ABSTRACT

In a trailing arm suspension for a vehicle, an axle carrier is fitted to the wheel-side end of a trailing arm, and an axle bearing is fitted to the axle carrier. The axle carrier includes a first flat plate-like member and a second flat plate-like member. The first flat plate-like member is arranged in substantially the longitudinal direction of the vehicle. The axle bearing is fitted to the first flat plate-like member. The second flat plate-like member is fixed to the front end of the first flat plate-like member at an angle at or around 90 degrees. The second flat plate-like member is fixed to the wheel-side end of the trailing arm at an angle within the range of 60 degrees to 90 degrees.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the structure of a trailing armsuspension that is used in a vehicle. More specifically, the inventionrelates to the structure of a lightweight and high-performance trailingarm suspension and a lightweight and high-performance axle carrier.

2. Description of the Related Art

Japanese Patent Application Publication No. JP-A-08-197926 describes thestructure of a trailing arm suspension in which a curved trailing arm isdirectly welded to an axle carrier.

Japanese Patent Application Publication No. JP-A-2004-322913 describesthe structure of a trailing arm suspension in which a longer trailingarm is provided so as to be passed through and fixed to an axle carrier.

FIG. 1 schematically illustrates the positional relationship between atrailing arm T and an axle carrier S, in the lateral direction of avehicle, in a trailing arm suspension. FIG. 1 shows a right rear wheelviewed from the top of the vehicle.

The wheel-side end of the trailing arm T is directly welded to the axlecarrier S in order to provide a lightweight trailing arm suspensionhaving high stiffness. In such structure, the axle carrier S is aplate-like member that extends in substantially the longitudinaldirection of the vehicle, as shown in FIG. 1. An axle bearing (notshown), which rotatably supports a wheel W, is fitted to the outboardside of the axle carrier S. Also, the wheel-side end of the trailing armT is directly welded to the inboard side of the axle carrier S.

In order to function well, the trailing arm T needs to extend insubstantially the longitudinal direction of the vehicle. Also, thetrailing arm T needs to be fitted a vehicle body so as to be pivotable,in substantially the vertical direction of the vehicle, about an axisthat extends in substantially the lateral direction of the vehicle.Consequently, an angle θ₁, which the trailing arm T forms with the axlecarrier S when the wheel-side end of the trailing arm T is butt-weldedto the axle carrier S, is small, as shown in FIG. 1.

However, decreases in the angle, at which the trailing arm T buttsagainst the axle carrier S, reduce ease in the welding operation.Accordingly, with the structure, in which the wheel-side end of thetrailing arm T is directly welded to the axle carrier S, thebutt-welding operation is difficult to perform.

FIG. 2 schematically illustrates the positional relationship between atrailing arm T and an axle carrier S, in the vertical direction of avehicle, in a trailing arm suspension. FIG. 2 illustrates the side viewof a right rear wheel viewed from a position inboard of the axle carrierS. FIG. 2 shows the structure for a four-wheel drive vehicle in whichthe axle carrier S has a drive shaft fitting structure D.

As shown in FIG. 2, when the structure, in which the wheel-side end ofthe trailing arm T is directly welded to the axle carrier S, is employedin a four-wheel drive vehicle, the trailing arm T passes through and isdirectly welded to the axle carrier S, at a position below a holethrough which the drive shaft is fitted. Accordingly, the length of thetrailing arm T needs to be longer in the backward direction of thevehicle, in comparison to when this structure is employed in afront-wheel drive vehicle. Also, in the trailing arm suspensionstructure used for the four-wheel drive vehicle above, the length of theaxle carrier S needs to be longer in the downward direction of thevehicle. In other words, the axle carrier S for the front-wheel drivevehicle and the axle carrier S for the four-wheel drive vehicle cannotshare the same design. Also, the axle carrier S for the four-wheel drivevehicle is heavier than the axle carrier S for the front-wheel drivevehicle.

Although not shown in FIG. 1, a harness of an ABS sensor, which extendsfrom the axle bearing (not shown) fitted to the outboard side of theaxle carrier S, is routed to the inside of the vehicle throughthrough-holes formed in the axle carrier S and the trailing arm T in thetrailing arm suspension. However, routing the harness in such a mannermakes it difficult to attach/detach a connector.

SUMMARY OF THE INVENTION

The invention provides a structure of a lightweight and high-performancetrailing arm suspension and a lightweight and high-performance axlecarrier.

A first aspect of the invention relates to an axle carrier of a trailingarm suspension for a vehicle, which is fitted to the wheel-side end of atrailing arm, and to which an axle bearing is fitted. The axle carrierincludes a first flat plate-like member and a second flat plate-likemember. The first flat plate-like member is arranged in a substantiallylongitudinal direction of the vehicle. The axle bearing is fitted to thefirst flat plate-like member. The second flat plate-like member isconnected to the front end of the first flat plate-like member at anangle that falls within a first predetermined angle range. The secondflat plate-like member is connected to the wheel-side end of thetrailing arm at an angle that falls within a second predetermined anglerange.

In the first aspect of the invention, the first flat plate-like memberand the second flat plate-like member may be integrally formed with eachother, for example, by press working.

In the first aspect of the invention, the first predetermined anglerange may be from 60 degrees to 90 degrees. Thus, the axle carrieraccording to the first aspect of the invention can be used in bothfront-wheel drive vehicles and four-wheel drive vehicles. Also, thespace for arranging a drive shaft is ensured.

In the first aspect of the invention, the second predetermined anglerange may be from 60 degrees to 90 degrees. Thus, the butt-weldingoperation can be performed easily.

According to the first aspect of the invention, a sufficiently largeangle, which the trailing arm forms with the face of the axle carrier towhich the trailing arm is fitted, is ensured. Accordingly, the weldingoperation is easier to perform.

According to the first aspect of the invention, the trailing arm is notpresent in the space inboard of the first flat plate-like member in thelateral direction of the vehicle. Accordingly, this space can be used toarrange the drive shaft or to route a harness of an ABS sensor. Thus,the axle carrier can be used in both four-wheel drive vehicles andfront-wheel drive vehicles. It is also easier to attach/detach aconnector.

According to the first aspect of the invention, the position, at whichthe trailing arm is welded to the axle carrier, is closer to the frontof the vehicle than that of the related art. Accordingly, it is possibleto use a trailing arm that is shorter than that of the related art,which reduces the weight and improves the stiffness of the trailing armsuspension.

The axle carrier according to the first aspect of the invention mayfurther include a reinforcing member that is fixed to the first flatplate-like member and the trailing arm. In this case, the reinforcingmember may be integrally formed with the first flat plate-like member,and/or the reinforcing member may be fixed to the second flat plate-likemember.

A second aspect of the invention relates to a trailing arm suspensionstructure for a vehicle, which includes right and left trailing armsthat are fitted to a vehicle body frame via respective elastic members;and axle carriers which are fitted to the wheel-side ends of therespective trailing arms, and to which respective axle bearings arefitted. Each axle carrier includes a first flat plate-like member and asecond flat plate-like member. The first flat plate-like member isarranged in a substantially longitudinal direction of the vehicle. Theaxle bearing is fitted to the first flat plate-like member. Thewheel-side end of the trailing arm is fitted to the second flatplate-like member. The second flat plate-like member is connected to thefront end of the first flat plate-like member at an angle that fallswithin a first predetermined angle range. The wheel-side end of thetrailing arm is connected to the second flat plate-like member at anangle that falls within a second predetermined angle range.

In the second aspect of the invention, the first flat plate-like memberand the second flat plate-like member may be integrally formed with eachother.

In the second aspect of the invention, the first predetermined anglerange may be from 60 degrees to 90 degrees. Thus, the trailing armsuspension structure according to the second aspect can be used in bothfront-wheel drive vehicles and four-wheel drive vehicles. Also, thespace for arranging a drive shaft is ensured.

In the second aspect of the invention, the second predetermined anglerange may be from 60 degrees to 90 degrees. Thus, the butt-weldingoperation can be easily performed.

According to the second aspect of the invention, a sufficiently largeangle, which the trailing arm forms with the face of the axle carrier towhich the trailing arm is fitted, is ensured. Accordingly, the weldingoperation is easier to perform.

According to the second aspect of the invention, the trailing arm is notpresent in the space inboard of the first flat plate-like member in thelateral direction of the vehicle. Accordingly, this space can be used toarrange the drive shaft or to route a harness of an ABS sensor. Thus,the axle carrier can be used in both four-wheel drive vehicles andfront-wheel drive vehicles. Also, it becomes easier to attach/detach aconnector.

According to the second aspect of the invention, the position, at whichthe trailing arm is welded to the axle carrier, is closer to the frontof the vehicle than that of the related art. Accordingly, it is possibleto use a trailing arm that is shorter than that of the related art,which reduces the weight and improves the stiffness of the trailing armsuspension.

The trailing arm suspension structure according to the second aspect ofthe invention may further include a reinforcing member that is fixed tothe first flat plate-like member and the trailing arm. In this case, thereinforcing member may be integrally formed with the first flatplate-like member, and/or the reinforcing member may be fixed to thesecond flat plate-like member.

The invention thus provides the structure of a lightweight andhigh-performance trailing arm suspension and a lightweight andhigh-performance axle carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and further objects, features and advantages of theinvention will become apparent from the following description of exampleembodiments with reference to the accompanying drawings, wherein thesame or corresponding portions will be denoted by the same referencenumerals and wherein:

FIG. 1 is the top view of a right rear wheel, schematically showing themanner in which a trailing arm is fitted to an axle carrier in, atrailing arm suspension structure according to a related art;

FIG. 2 is the side view of a right rear wheel viewed from a positioninboard of an axle carrier, schematically showing the manner in which atrailing arm is fitted to the axle carrier in a trailing arm suspensionstructure according to another related art;

FIG. 3 is the view schematically showing an axle carrier for a trailingarm suspension according to an embodiment of the invention, when viewedfrom the top of a vehicle;

FIG. 4 is the side view showing the axle carrier for the trailing armsuspension according to the embodiment of the invention, when viewedfrom a position inboard of the axle carrier;

FIG. 5 is the perspective view showing the axle carrier for the trailingarm suspension according to a first modified example of the embodimentof the invention, when viewed from a position inboard of and above theaxle carrier, and diagonally to the rear of the axle carrier;

FIG. 6 is the perspective view showing the axle carrier for the trailingarm suspension according to the first modified example of the embodimentof the invention, when viewed from a position outboard of and above theaxle carrier, and diagonally to the front of the axle carrier;

FIG. 7 is the side view showing the axle carrier for the trailing armsuspension according to the first modified example of the embodiment ofthe invention, when viewed from a position inboard of the axle carrier;

FIG. 8 is the perspective view showing the axle carrier for the trailingarm suspension according to a second modified example of the embodimentof the invention, when viewed from a position inboard of and above theaxle carrier, and diagonally to the rear of the axle carrier;

FIG. 9 is the side view showing the axle carrier for the trailing armsuspension according to the second modified example of the embodiment ofthe invention, when viewed from a position outboard of and above theaxle carrier, and diagonally to the front of the axle carrier; and

FIG. 10 is the perspective view showing the axle carrier for thetrailing arm suspension according to the second modified example of theembodiment of the invention, when viewed from a position inboard of theaxle carrier.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Hereafter, an example embodiment of the invention will be described withreference to accompanying drawings. Because well known to personsskilled in the art pertinent to the invention, the basic concept, themain hardware configurations, and the operation principal of trailingarm suspensions will not be described below in detail.

Hereafter, a trailing arm suspension structure and an axle carrier usedin the trailing arm structure according to the embodiment of theinvention will be described with reference to FIGS. 3 to 10. The same orcorresponding components will be denoted by the same reference numeralsin FIGS. 3 to 10.

FIGS. 3 and 4 schematically illustrate the trailing arm suspensionstructure according to the embodiment. FIG. 3 illustrates the top viewof a right rear wheel. FIG. 4 illustrates the side view of the rightrear wheel, when viewed from a position inboard of the axle carrier. Forconvenience of explanation, only an axle carrier 301, a trailing arm302, and a wheel 303 are shown in FIGS. 3 and 4. Other components suchas an axle bearing, which is fitted to the axle carrier 301 and whichrotatably supports the wheel 303, are not shown in FIGS. 3 and 4.

As shown in FIG. 3, the axle carrier 301 according to the embodiment isa substantially L-shaped member. The axle carrier 301 is formed mainlyof a first flat plate-like portion 301 a, which is arranged insubstantially the longitudinal direction of the vehicle; and a secondflat plate-like portion 301 b, which is arranged in substantially thelateral direction of the vehicle.

When viewed from the top of the vehicle, namely, on the planesubstantially parallel to the ground surface, the first flat plate-likeportion 301 a and the second flat plate-like portion 301 b are connectedto each other at or around 90 degree angle, thereby forming asubstantially L-shape. The vertically-extending front end of the firstflat plate-like portion 301 a and the vertically-extending outboard endof the second flat plate-like portion 301 b are integrally fixed to eachother in the vertical direction of the vehicle. If the angle, which thefirst flat plate-like portion 301 a forms with the second flatplate-like portion 301 b (i.e., the central angle of the L-shape), iswithin the range from 60 degrees to 90 degrees, when viewed from the topof the vehicle, the welding operation can be performed easily. As thisangle approaches 90 degrees, it becomes easier to perform the weldingoperation. However, the angle is not limited to a certain value, as longas the axle carrier 301 according to the embodiment can be used in bothfour-wheel drive vehicles and front-wheel drive vehicles.

In the embodiment, the first flat plate-like portion 301 a and thesecond flat plate-like portion 301 b are integrally formed with eachother, as a single rigid member (i.e., the axle carrier 301), as shownin FIG. 3. Alternatively, the first flat plate-like portion 301 a andthe second flat plate-like portion 301 b may be prepared as separate tworigid members, and the axle carrier 301 may be formed by connectingthese two portions 301 a, 301 b, for example, by welding.

The axle bearing (not shown) is fitted to the outboard side of the firstflat plate-like portion 301 a. Then, the wheel 303 is fitted to theoutboard side of the axle bearing.

The wheel-side end of the trailing arm 302 is butt-welded to the frontside of the second flat plate-like portion 301 b.

With the structure and configuration according to the embodimentdescribed above, a sufficiently large angle θ₂, which the trailing arm302 forms with the face of the axle carrier 301 (the front side of thesecond flat plate-like portion 301 b) to which the trailing arm 302 isfitted, is ensured. Accordingly, the welding operation is easier toperform. If the angle θ₂ is within the range from 60 degrees to 90degrees, the welding operation can be easily performed. In particular,the closer the angle θ₂ is to 90 degrees, the easier the weldingoperation becomes.

According to the embodiment, the trailing arm 302 is not present in thespace inboard of the first flat plate-like portion 301 a in the lateraldirection of the vehicle. Accordingly, a drive shaft fitting structure304 may be formed in the first flat plate-like portion 301 a, and adrive shaft 305 (indicated by the dashed lines in FIG. 3) may beprovided in this space. Alternatively, this space may be used to route aharness of an ABS sensor (not shown). When the drive shaft fittingstructure 304 is formed in the flat plate-like portion 301 a and thedrive shaft 305 is provided in the space, the trailing arm suspensionstructure and the axle carrier according to the embodiment can be usedin both four-wheel drive vehicles and front-wheel drive vehicles. Also,routing the harness of the ABS sensor through the space makes it easierto attach/detach a connector.

According to the embodiment, the position, at which the trailing arm 302is welded to the axle carrier 301, is closer to the front of the vehiclethan that of the related art, as shown in FIGS. 3 and 4. Accordingly,the trailing arm 302 may be shorter than that of the related art, whichreduces the weight and improves stiffness of the trailing armsuspension.

In the embodiment, at least one rigid body serving as a reinforcingmember (not shown in FIGS. 3 and 4, because this is not an essentialcomponent), which is separate from the axle carrier 301, may be fixed toboth the axle carrier 301 and the trailing arm 302. Thus, connectionbetween the axle carrier 301 and the trailing arm 302 is reinforced.Alternatively, such a reinforcing member may be integrally formed withone of the axle carrier 301 and the trailing arm 302.

Next, the axle carrier for the trailing arm suspension according tomodified examples of the embodiment will be described in detail. FIGS. 5to 7 show the first modified example, and FIGS. 8 to 10 show the secondmodified example. Each modified example shows the structure for theright rear wheel. Each of FIGS. 5 and 8 is the perspective view of theaxle carrier 301 when viewed from a position inboard of and above theaxle carrier 301, and diagonally to the rear of the axle carrier 301.Each of FIGS. 6 to 9 is the perspective view of the axle carrier 301when viewed from a position outboard of and above the axle carrier 301,and diagonally to the front of the axle carrier 301. Each of FIGS. 7 and10 is the side view of the axle carrier 301, when viewed from a positioninboard of the axle carrier 301. The components in FIGS. 5 to 10, whichcorrespond to the components according to the embodiment schematicallyshown in FIGS. 3 and 4, are denoted by the same reference numerals as inFIGS. 3 and 4.

As shown in FIGS. 5 to 7, in the first modified example, the axlecarrier 301 is formed of the first flat plate-like portion 301 a, towhich the axle bearing is fitted; the second flat plate-like portion 301b, to which the trailing arm 302 is fitted; and reinforcing portions 501a and 501 b.

The axle carrier 301 is welded to the wheel-side end of the trailing arm302, as shown in FIG. 5. A bushing collar 502, which houses a bushingprovided between the trailing arm 302 and a vehicle body, is formed atthe vehicle-body-side end of the trailing arm 302.

In the first modified example, the first flat plate-like portion 301 a,the second flat plate-like portion 301 b, and the reinforcing portions501 a and 501 b are formed from a single metal member, and formed, forexample, by press working. However, some or all of these portions may beprepared as separate rigid members, and welded together.

The reinforcing portion 501 includes the upper reinforcing portion 501 aand the lower reinforcing portion 501 b. The upper reinforcing portion501 a extends from the top end of the first flat plate-like portion 301a, and is welded to the top portion of the trailing arm 302 and the topface of the second flat plate-like portion 301 b. The lower reinforcingportion 501 b extends from the bottom end of the first flat plate-likeportion 301 a, and is welded to the bottom portion of the trailing arm302 and the bottom face of the second flat plate-like portion 301 b.

Provision of such reinforcing portions 501 a and 501 b allows thetrailing arm 302 and the axle carrier 301 to be connected to each othermore stiffly, and the stiffness of the trailing arm suspension to beimproved.

The upper reinforcing portion 501 a and the lower reinforcing portion501 b may be prepared as rigid members, which are separate from thefirst flat plate-like portion 301 a and the second flat plate-likeportion 301 b. Then, each of the upper reinforcing portion 501 a and thelower reinforcing portion 501 b may be welded to both the first flatplate-like portion 301 a and the second flat plate-like portion 301 b.

As shown in FIGS. 8 to 10, in the second modified example, the axlecarrier 301 is formed of the first flat plate-like portion 301 a, towhich the axle bearing is fitted; the second flat plate-like portion 301b, to which the trailing arm 302 is fitted, first reinforcing portions501′a and 501′b, and a second reinforcing member 801.

The axle carrier 301 is welded to the wheel-side end of the trailing arm302, as shown in FIG. 8. The bushing collar 502, which houses thebushing provided between the trailing arm 302 and the vehicle body, isformed at the vehicle-body-side end of the trailing arm 302.

The first reinforcing portions 501′a and 501′b are shorter than thereinforcing portions 501 a and 501 b, respectively, in the firstmodified example in the longitudinal direction of the reinforcingportions. Although the first reinforcing portions 501′a and 501′b areconnected to the second flat plate-like portion 301 b, they are notwelded to the trailing arm 302.

The second reinforcing member 801 is prepared as a separate member fromthe first flat plate-like portion 301 a, the second flat plate-likeportion 301 b, and the first reinforcing portions 501′a and 501′b. Thesecond reinforcing member 801 is positioned outboard of the axle carrier301 and the trailing arm 302. The second reinforcing member 801 iswelded to the outboard side of the first flat plate-like portion 301 aand the trailing arm 302 such that the reinforcing member 801 extendssubstantially horizontally.

As shown in FIG. 9, the second reinforcing member 801 is welded so as tosubstantially entirely cover the outboard side of the first flatplate-like portion 301 a. Also, the second reinforcing member 801 andthe first flat plate-like portion 301 a constitute the drive shaftfitting structure 304. Namely, in the second modified example, thesecond reinforcing member 801 is arranged between the first flatplate-like portion 301 a and the axle bearing (not shown) in the lateraldirection of the vehicle.

Provision of such reinforcing portions 501′a and 501′b allows a stifferconnection between the trailing arm 302 and the axle carrier 301, and aimproved stiffness of the trailing arm suspension.

The first flat plate-like portion 301 a, the second flat plate-likeportion 301 b and the first reinforcing portions 510′a and 501′b areprepared as a single piece of metal member, and formed, for example, bypress working. However, some or all of these portions may be prepared asseparate rigid members, and welded to each other.

The invention can be applied to the trailing arm suspension structureand the axle carrier used in the structure, regardless of theappearance, weight, size, running performance, etc. of the vehicleincluding the trailing arm suspension.

While the invention has been described with reference to exampleembodiments thereof, it is to be understood that the invention is notlimited to the example embodiments or constructions. To the contrary,the invention is intended to cover various modifications and equivalentarrangements. In addition, while the various elements of the exampleembodiments are shown in various combinations and configurations, whichare exemplary, other combinations and configurations, including more,less or only a single element, are also within the spirit and scope ofthe invention.

1-14. (canceled) 15: A trailing arm suspension structure for a vehicle,comprising a trailing arm and an axle carrier that is fitted to atrailing arm end located next to which an axle bearing is fitted, theaxle carrier comprising: a first flat plate-like member which isarranged in a substantially longitudinal direction of the vehicle, andto which the axle bearing is fitted; and a second flat plate-like memberwhich is fixed to a front end of the first flat plate-like member at anangle that falls within a range from 60 degrees to 90 degrees, whereinthe trailing arm end located next to the axle carrier is butt-welded tothe front side of the second plate-like member at an angle that fallswithin a range from 60 degrees to 90 degrees. 16: The trailing armsuspension structure according to claim 15, wherein the first flatplate-like member and the second flat plate-like member are integrallyformed with each other. 17: The trailing arm suspension structureaccording to claim 15, the axle carrier further comprising: areinforcing member that is fixed to the first flat plate-like member andthe trailing arm. 18: The trailing arm suspension structure according toclaim 16, the axle carrier further comprising a reinforcing member thatis fixed to the first flat plate-like member and the trailing arm. 19:The trailing arm suspension structure according to claim 17, wherein thereinforcing member is integrally formed with the first flat plate-likemember. 20: The trailing arm suspension structure according to claim 18,wherein the reinforcing member is integrally formed with the first flatplate-like member. 21: The trailing arm suspension structure accordingto claim 17, wherein the reinforcing member is integrally formed withthe first flat plate-like member. 22: The trailing arm suspensionstructure according to claim 19, wherein the reinforcing member is fixedto the second flat plate-like member. 23: The trailing arm suspensionstructure according to claim 20, wherein the reinforcing member is fixedto the second flat plate-like member. 24: The trailing arm suspensionstructure according to claim 21, wherein the reinforcing member is fixedto the second flat plate-like member. 25: A trailing arm suspensionstructure for a vehicle, comprising: right and left trailing arms thatare fitted to a vehicle body frame via respective elastic members; andaxle carriers that are fitted to the respective trailing arm endslocated next to the axle carriers, and to which respective axle bearingsare fitted, wherein each of the axle carriers includes a first flatplate-like member arranged in a substantially longitudinal direction ofthe vehicle, and to which the axle bearing is fitted; and a second flatplate-like member fixed to a front end of the first flat plate-likemember at an angle that falls within a range from 60 degrees to 90degrees, and the trailing arm end located next to a respective axlecarrier is butt-welded to the front side of the second flat plate-likemember of the respective axle carrier at an angle that falls within therange from 60 degrees to 90 degrees. 26: The trailing arm suspensionstructure according to claim 25, wherein the first flat plate-likemember and the second flat plate-like member are integrally formed witheach other. 27: The trailing arm suspension structure according to claim25, further comprising: a reinforcing member that is fixed to the firstflat plate-like member and the trailing arm. 28: The trailing armsuspension structure according to claim 26, further comprising: areinforcing member that is fixed to the first flat plate-like member andthe trailing arm. 29: The trailing arm suspension structure according toclaim 27, wherein the reinforcing member is integrally formed with thefirst flat plate-like member. 30: The trailing arm suspension structureaccording to claim 28, wherein the reinforcing member is integrallyformed with the first flat plate-like member. 31: The trailing armsuspension structure according to claim 27, wherein the reinforcingmember is fixed to the second flat plate-like member. 32: The trailingarm suspension structure according to claim 28, wherein the reinforcingmember is fixed to the second flat plate-like member. 33: The trailingarm suspension structure according to claim 29, wherein the reinforcingmember is fixed to the second flat late-like member. 34: The trailingarm suspension structure according to claim 30, wherein the reinforcingmember is fixed to the second flat plate-like member.